1. Field of the Invention
This invention relates to a so-called metal-in-gap type magnetic head including a pair of magnetic core halves with its gap portion made of a metal magnetic film. Particularly, it relates to a magnetic head in which the metal magnetic film has a multilayer structure formed by first forming a multilayer film by stacking Fe--M--N magnetic thin film layers and precious metal layers such as Pt layers and then stacking such multilayer films via an insulating film, so as to improve reproduction output to make the magnetic head suitable for recording on and reproduction from a magnetic recording medium having a large coercive force, such as, a so-called metal tape.
2. Description of the Related Art
Recently, as the recording density of signals has become higher in the field of magnetic recording, magnetic recording media having a large coercive force and a high remanent magnetic flux density are used, such as, metal tapes manufactured by directly coating a non-magnetic support with a ferromagnetic metal material. Accordingly, core materials for magnetic heads are required to have a high saturation magnetic flux density and high permeability.
To meet such requirements, a metal-in-gap type magnetic head (hereinafter referred to as a MIG head) has been proposed in which ferrite is used as a sub-core material while a metal magnetic film having a high saturation magnetic flux density is formed as a main core material formed on the ferrite so that a magnetic gap portion is formed by the metal magnetic film. The MIG head is suitable for recording on and reproduction from a metal tape.
Meanwhile, in accordance with the significant progress in higher recording density in recent years, the magnetic head of the above-described type is required to employ a metal magnetic material which has a higher saturation magnetic flux density for obtaining a large recording magnetic field and exhibits soft magnetic property in order to carry out more satisfactory recording on and reproduction from a magnetic recording medium having a large coercive force, such as, the metal tape.
Also, since a microcrystal metal magnetic film containing Fe as its main component has a high saturation magnetic flux density and exhibits excellent soft magnetic property in the in-plane direction, the microcrystal metal magnetic film has been put into practical use in place of the conventional metal magnetic material for the magnetic head.
However, in the MIG head, though the microcrystal metal magnetic film mainly containing Fe is formed on ferrite in place of the conventional metal magnetic film, the soft magnetic property in the direction of thickness as well as the soft magnetic property in the in-plane direction is important. Therefore, the head efficiency has not been so improved as expected from the excellent soft magnetic property in the in-plane direction of the microcrystal metal magnetic film, and the reproduction output has not been so improved, either.
Thus, the present applicant has already proposed a magnetic head including a pair of magnetic core halves joined and integrated with each other with magnetic gap forming surfaces thereof abutted to each other, and a metal magnetic film formed on the magnetic gap forming surface of at least one of the pair of magnetic core halves, in which the metal magnetic film is made of a multilayer film of stacked magnetic thin film layers having composition of Fe.sub.x M.sub.y N.sub.z and Pt layers, with M being at least one selected from Ta, Zr, Hf, Nb, Ti, Mo and W, and x, y and z indicating atomic percentages and holding relations of 71.ltoreq.x .ltoreq.85, 6.ltoreq.y.ltoreq.15, and 9.ltoreq.z.ltoreq.16. (See the Japanese Patent Application No.8-12956.)